Just as writing with my right hand eventually makes it hurt, while my left hand enjoys a relative stress-free life, my heart's left ventrical does much more work and is more stressed than my heart's right ventrical.
Because of the demand on the left heart, it also is larger, consumes more oxygen and is more vulnerable to oxygen imbalance. The lungs empty into the left heart so if it's not functioning to par, its possible it is unable to deliver blood to the circulation in the body. In addition to causing cerebral hypoxia, compromised systemic circulation decreases perfusion of kidneys activating the renin-angiotensin-aldosterone system. Angiotensin II increases peripheral resistance putting more strain on the left heart.
In most cases of heart failure, the left heart fails first. The right heart follows. But it is possible for the right heart to fail independently in primary lung diseases when pressure load on the right heart increases significantly.
Independent right-side heart failure can occur when there is resistance in the lung's vascular bed. The congestion of capillary beds include hepatomegaly and splenomegaly. Congestion of kidneys can decrease perfusion more than as would occur in left heart failure, resulting in increased fluid retention, edema, accumulation of impurities and waste. In time, the left heart will follow.
Reference ListNowak TJ, Handford AG. Pathophysiology: Concepts and Applications for Health Professionals. New York: McGraw-Hill, 2004, p255.
